Why do I get an Access error #Name? in my form footer?

I have an Access query BookingWeeklyTotal with Column names of Total and Expr1

I have a subform called BookingCurrentDay that lists all the details of an order booked on the current day.

In the form footer of the subform I put a text box. I want the text box to add all the orders of the week taken from the
query BookingWeeklyTotal. In the text box I use the Name field = Total and the Control Source I put =BookingWeeklyTotal![Total]

I  get an Access error #Name?  What am I doing wrong?

Thank you